Apparatus and method for originating call by substitute communication network when originating call is barred

1. A portable terminal for originating a call, the portable terminal comprising:

a reception unit to receive from a base station a message barring originating a call in a first network;

a storage unit to store a first information, the first information being information of one or more cells of a second network included in a system information block (SIB) message and the storage unit storing the first information in a second network database;

an input unit to receive a request to originate a call;

a control unit to select a cell in the storage unit with a power level higher than a preset value if originating the call is barred in the first network; and

a transmission unit to originate the call in the selected cell,

wherein the control unit comprises:

a communication mode switching unit to switch a communication mode from the first network to a second network if originating the call is barred in the first network;

a cell searching unit to search for cells in the second network database and measure power levels of the searched cells; and

a cell selecting unit to select a searched cell if the power level of the searched cell is higher than the preset value.

2. The portable terminal of claim 1 , wherein the storage unit stores a second information, the second information being information of one or more cells of a second network previously used by the portable terminal.

3. The portable terminal of claim 1 , wherein the first network is an LTE network and the second network is one of a 3G network and a 2G network.

4. The portable terminal of claim 2 , wherein the storage unit stores the second information in the second network database, the second network database comprising at least one of a 3G network database and a 2G network database.

5. The portable terminal of claim 1 , wherein the cell selecting unit selects a searched cell with the highest power level if the highest power level is higher than the preset value.

6. The portable terminal of claim 5 , wherein, if the highest power level is lower than the preset value, the cell searching unit searches for cells of the second network not stored in the second network database, and

the cell selecting unit selects a searched cell of the second network not stored in the second network database if the power level of the searched cell is higher than the preset value.

7. The portable terminal of claim 1 , wherein the communication mode switching unit switches from the second network to a different second network if originating the call is barred in the second network.

8. The portable terminal of claim 7 , wherein the communication mode switching unit switches the communication mode from the LTE network to the 3G network if originating the call is barred in the LTE network, and

the communication mode switching unit switches the communication mode from the 3G network to the 2G network if originating a call is barred in the 3G network.

9. The portable terminal of claim 1 , wherein the transmission unit originates a circuit-switched (CS) call if a voice call is requested and originates a packet-switched (PS) call if a data call is requested.

10. A method to originate a call, the method comprising:

receiving from a base station a message barring originating a call in a first network;

storing a first information in a second network database, the first information being information of one or more cells of a second network included in a system information block (SIB) message;

receiving a request to originate a call;

selecting a cell among the cells corresponding to the stored first information with a power level higher than a preset value if originating the call is barred in the first network; and

originating the call in the selected cell,

wherein selecting of the cell comprises:

switching a communication mode from the first network to a second network in response to originating the call being barred in the first network;

searching for cells in the second network database and measuring power levels of the searched cells; and

selecting a searched cell with a power level higher than the preset value.

11. The method of claim 10 , further comprising storing a second information, the second information being information of one or more cells of a second network previously used by the portable terminal.

12. The method of claim 11 , further comprising storing the second information in the second network database.

13. The method of claim 10 , further comprising selecting a searched cell with the highest power level if the highest power level is higher than the preset value.

14. The method of claim 13 , wherein, if the highest power level is lower than the preset value, searching for cells in the second network not stored in the second network database, and

selecting a searched cell in the second network not stored in the second network database if the power level of the searched cell is higher than a preset value.

15. The method of claim 10 , further comprising switching the communication mode from the second network to a different second network if originating the call is barred in the second network.

16. The method of claim 15 , further comprising switching the communication mode from the LTE network to the 3G network if originating a call is barred in the LTE network, and

switching the communication mode from the 3G network to the 2G network if originating a call is barred in the 3G network.

17. The method of claim 10 , wherein the call is originated as a circuit-switched (CS) call if a voice call is requested and originated as a packet-switched (PS) call if a data call is requested.